Oil filters of various constructions and shapes are known to provide for filtration of oil in an oil circulating system.
In current internal combustion engine constructions for automotive vehicles, it is the prevailing practice to employ a standard oil filter attachment or fitting to accommodate disposable oil filter canisters which are threadably attached to and removed from the engine block in rapid and efficient manner. Such standardized fittings comprise a central oil flow pipe which is externally threaded and extends a short distance outwardly of the engine block. Oil flow passageways are provided in the engine block in radial disposition about the central threaded pipe for circulation of the engine oil through the filter canister and between the pipe and engine block passageways for filtration. The disposable filter canisters are provided with an end wall having a central opening which is internally threaded to be received on the engine oil flow pipe, and radially disposed openings about the central opening in the end wall for circulation of the oil therethrough. Such disposable oil filter canisters, although relatively simple to attach and remove from the engine block oil fitting, constitute a considerable expense in the long run operational expense of an automotive vehicle, since they are a composite unit which is totally discarded and replaced with a new canister each time the oil filter is renewed.
Certain oil filter constructions are known which comprise a filter housing with removable filter medium, and with oil inlets and outlets provided in the housing to direct flow of oil through the filter medium and return it to the oil system for use. Certain of such replaceable filter medium filter units are provided with a removable end cap for access to the filter housing to permit replacement of the filter medium periodically during use. Oil filter unit constructions having provision for replacement of the filter medium therein are disclosed in the following U.S. Patents: U.S. Pat. No. 2,661,846--Lash et al U.S. Pat. No. 2,738,879--Frantz U.S. Pat. No. 2,933,192--Gretzinger U.S. Pat. No. 2,951,587--Carpenter U.S. Pat. No. 3,069,015--Hultgren et al U.S. Pat. No. 3,282,429--Wood et al U.S. Pat. No. 3,526,590--Russo
The oil filter unit constructions disclosed in the abovementioned patents generally have oil inlets and outlets in the filter housing, and end cap attachment means, which are so located and arranged as to require substantial modification of the standard oil filter fitting which is currently employed on automotive engines to accommodate the aforementioned disposable filter canisters.